won't even offer to bring one in for you? So much for local service!
Try drsfostersmith.com, marinedepot.com, premiumaquatics.com, ... shoot, just about any online place will have them.
Do NOT use copper at low salinity. Either do one or the other, but not both. My vote would be to leave the fish at the existing salinity until you get a refractometer, then continue with the hyposalinity treatment. Otherwise, SLOWLY increase the salinity over many days as noted in that link I gave you, until you're back at your normal tank salinity. Then do the copper treatment. But even to slowly raise the salinity by 1 or 2 points a day is going to be tough without a refractometer.